Glow transfer tube driving circuit



6, 1953 J. E. ADAMS 2,849,655

GLOW TRANSFER TUBE DRIVING CIRCUIT Filed Oct. 31, 1956 i INVENTOR.

*1, JOHN E. ADAMS Fig. 2

ATTOR NEYS GLOW TSFER TUKBE DRIVING CIRCUIT John E. Adams, Newtonville, Mass, assignor to Sylvania Electric Products Inc, Salem, Mass, a corporation of Massachusetts Application October 31, 1956, Serial No. 619,536 9 Claims. (Cl. $15-$46) This invention relates to electronic counting devices and particularly to drive circuits for gas-filled glow transfer counting tubes.

In general, the gas-filled glow transfer counting tubes presently known include an anode and groups of cathodic electrodes. One set of the cathodic electrodes serves as the main or count-indicating cathodes, and the other sets of cathodic electrodes serve as guide electrodes or guides. A glow discharge takes place between the anode and one of the main or count indicating cathodes. The particular main cathode at which the glow is taking place at a given instant is indicative of the count. When several of the tubes are incorporated in a decimal counting system, it is possible at a given instant to read out the count in tens by determining visually or otherwise the particular main cathode of each tube at which the glow is taking place. Switching from one main cathode to the next occurs usually in response to pulsed signals representing the quantities to be counted. The signals may be of any number of numerous varieties in waveshape, repetition rate or duration.

Ideally, transfer of the glow discharge from one main cathode directly to the next would be accomplished in immediate response to an input signal. It would appear that such a transfer could be accomplished readily by a suitable gas filling, and proper spacing of electrodes within the tube. However, it has been found that only under the most stringent conditions not only regarding the gas filling and the spacing of electrodes, but also regarding the type of voltages applied, could such a transfer be acomplished. To accommodate the counting tubes to pulses such as are more easily generated and normally encountered in computer and similar applications, it has been necessary to provide so-called guide electrodes between main cathodes to effect the transfer from one main cathode to the next. Numerous drive circuits have been designated to accommodate the counting tube to pulses of various durations, frequencies and wave shapes. A combination which has been widely used, involves the coupling of the drive circuits with counting tubes which include three guides between each main cathode and its neighboring main cathode.

The diificulties with such tubes and drive circuits are numerous but they may be summarized as follows: First, the range of frequencies or repetition rates are limited. Second, the wave shape of the input signal, particularly its duration must be ideal. Third, expensive multi-elemerit tubes have been required. Fourth, preamplification has often been necessary for pulses of low amplitude.

Therefore, it is an object of the present invention to provide a counting tube and driving circuit which are of simple construction.

Another object of the present invention is to provide a tube and driving circuit wherein the glow transfer from one cathode to the next is positive and occurs in response to a single input pulse.

Still another object of the present invention is to pro- 2,849,655 Patented Aug. 26, 1958 "ice a... vide a counting tube and driving circuit which are operable over a wide range of repetition frequencies.

A still further object is to provide a glow transfer counting tube in which actuation is had in response to pulses which are not idealized in Wave shape.

In general, the present invention consists in a drive circuit and counting tube wherein the glow discharge is transferred from a main cathode to a first guide and thence to a second guide in a given direction in response to an input pulse. The desired transfer is effected by either or both of two separate actions. A negative input pulse is simultaneously placed directly on the first guide and also across a voltage divider. The second guide is connected to a point on the voltage divider which causes only a predetermined portion of the applied input pulse to be present upon the second guide. Glow discharge current fiows between the anode of the counting tube and the first guide in response to the lowering of the voltage on that guide by the negative input pulse, A voltage is developed across a resistor in circuit with the first guide and this voltage charges a condenser which is connected in parallel with the resistor. The charge temporarily retained on the condenser causes the first guide to become, and remain for a period, more positive than the next most negative electrode in the tube which is the second guide to which the portion of the negative input pulse has been applied. Thus, immediately after application of the input pulse, there occurs a double transfer from the main cathode to the first guide and thence to the second guide. At about the time of cessation of the pulse, the transfer of the glow discharge to the next main cathode takes place. For a better understanding of the present invention together with other and further features and advantages, reference should be made to the following detailed description which should be read in connection with the accompanying drawings in which:

Fig. 1 is a schematic diagram of the tube and driving circuit of the present invention, and

Fig. 2 is a diagram of a typical voltage pulse to be counted by the present invention.

In Fig. 1 input terminals ll and 12 are the terminals to which the pulses to be counted are applied. A conventional coupling condenser 13 is connected to input terminal ll. Connected to the other side of coupling condenser 13 is a voltage divider which is composed of resistors 1d and 15. In addition to the voltage divider, there is also connected to the other side of coupling condenser 13, an RC circuit which is composed of the parallel combination of condenser 16 and resistor 17. The other side of the RC circuit is connected directly to the first guide transfer electrode 19 in counting tube 1%.

Counting tube 18, if it were designed in the conventional manner would include ten main cathodes, ten first guide electrodes, ten second guide electrodes, etc. for decimal counting. To avoid unduly complicating the drawing, counting tube 13 has been shown as a five stage device, but it will be understood that no particular limitation in number of stages is esesntial or even preferred except insofar as ten stages are adaptable to decimal counting.

All of the so-called first guides 19, Ma, 19b, 19c and 1% are bussed together. So also, are the second guides Zll, Zila, 2%, Zfic and Zild. Four of the main cathodes, namely, main cathodes 22, 21a, 21b and 21d are also bussed together and connected back to terminal 12 which may, as shown, be considered the grounded reference point for the entire circuit. Also, cathode 210 is designated as the output cathode and is returned to ground but through an output resistor 23 across which the output signal is developed.

. In the glow tube there is also an anode 25 which is connected to a source of positive anode potential 26 through an anode resistor 27. Output terminals 28 and 29 which are connected respectively to the ends of resistor 23 permit the extraction of an output signal.

The operation of the present invention may most easily be understood by reference to Fig. 2. Generally, Fig. 2 is a representation of one type of input pulse to which the present invention is responsive. It may be assumed for purposes of explanation that the glow discharge is taking place between anode 25 and cathode 21 and that the condenser 16 is discharged. Upon the occurrence of a pulse such as illustrated in Fig. 2, transfer action is initiated. The rectangular leading edge of the pulse is coupled directly through the condenser 16 to guide 19 because the voltage across that condenser cannot instantaneously change. The sudden lowering of the potential on guide 19 causes the glow discharge existing between anode 25 and cathode 21 to transfer immediately to guide 19 as is indicated at point 30 in Fig. 2. With the transfer of the glow discharge to guide 19, a current flows through the resistor 17. Condenser 16, being connected in parallel with resistor 17 and previously having been discharged, begins to charge. Furthermore, the voltage developed across resistor 17 by reason of the glow discharge current flowing therethrough causes guide 19 to become more positive than the next most negative electrode in th tube.

At the same time that condenser 16 is becoming charged, the negative input pulse which was applied to guide 19 is also present across the voltage divider composed of resistors 14 and 15. The value of resistor 14 is about one-third of that of resistor 15, although the ratio of values may be varied over a considerable range without affecting proper operation of the circuit. In the present case, however, with the ratio chosen, threequarters of the applied negative voltage appears on guide 20 at substantially the same time that the entire negative voltage appears on guide 19, This application of threea quarters of the applied input negative voltage to guide 20 makes certain that guide 20 becomes the next most negative electrode. When the voltage on guide 19 exceeds that on guide 20 by an amount greater than the transfer voltage of the tube, the glow discharge shifts from guide 19 to guide 20. This occurs at a point such as shown at 31, although the exact point in time at which the transfer takes place may be easily shifted by design changes.

As the input voltage pulse declines, the glow discharge shifts from second guide 20 to the next main cathode 21a as seen at 32. Suitable changes of circuit parameters permit point 32 to'be located at any one of a range of voltage values. This completes the cycle from one main cathode to the next in response to a single input pulse. Each additional pulse causes a similar shift from one main cathode to the next via the intervening guides. An example of a typical arrangement of counting tube and drive circuit includes as tube 18 a Sylvania Type 6476, condensers 13 and 16 having values of 0.1 micro-farad and 330 micro-microfarads, respectively. Resistor 14 is of 24 thousand ohms, resistor 15 of 75 thousand ohms, resistor 17 of 220 thousands ohms, and resistor 23 of 24 thousand ohms. The potential at terminal 26 is 400 volts, and the value of anode resistor 27 is 330 thousand ohms.

By way of summarizing the operation of the invention, it may be noted that when the glow discharge shifts from main cathode 21 to first guide 19, the dwell time of the glow on first guide 19 is affected primarily by two factors. One factor is the rise in voltage of guide 19 caused by voltage developed by the flow of current through resistor 17. The other factor is the presence of three-quarters of the applied negative voltage on guide 20. As soon as the voltage on guide 19 is more positive than that on guide 20 by an amount greater than the transfer voltage of the tube 18, the glow discharge moves on to guide 20.

. the glow discharge.

The next transfer of the glow discharge to main cathode 21a rather than back to guide 19 is assured by the fact that condenser 16 is not completely discharged. The time constant of the RC circuit which includes condenser 16 and resistor 17 is deliberately chosen to be of sufiicient length that a positive voltage is present on guide 19 as a result of condenser 16 discharging through resistor for a considerable period after the glow discharge leaves guide 19. Furthermore, any tendency of the glow to return to guide 19 is inhibited because as soon as any part of the discharge current flows through resistor 17 a positivegoing voltage is generated at guide 19 as a result of the drop across resistor 17. The value of the resistors in series with guide 19 is very much greater than those in series with the cathode so that even a relatively small portion of the glow current causes the development of a relatively large voltage which would repel the glow discharge from guide 19. Thus, positive movement .of the glow discharge in the direction indicated by the arrows is assured. The resistor 15 disposed in series with guide 20, may be of a value considerably larger than that of the resistors 14 and 23 to aid the final shift of the glow discharge from each of the second guides.

The output signal from the tube 18, which is developed each time the glow discharge reaches and leaves main cathode 210, indicates a traverse of the complete tube by Cascaded arrangements wherein ten stages exist in each tube may be conveniently set up to provide decimal system counting in this manner.

Although what has been disclosed is a presently preferred form of the invention, other modifications will suggest themeslves to those skilled in the art without departure from the concepts of the invention. The inventlon should be limited not to details disclosed but only by the spirit and scope of the appended claims.

What is claimed is:

1. A drive circuit for a glow discharge counting tube having a plurality of cathodes and first and second sets of guide electrodes comprising means for applying an input signal to said first set of guide electrodes, means for simultaneously applying a portion of said input signal to said second set of guide electrodes, and means for increasing the potential on said first set of guide electrodes in a positive direction after the transfer of said glow discharge to one of said first set of guide electrodes to cause the subsequent transfer of said glow discharge to one of said second set of guide electrodes.

2. A circuit as defined in claim 1 including means for maintaining the potential of said first set of guide electrodes at an increased positive value for a predetermined period after the transfer of said glow discharge thereto.

3. A drive circuit for a glow discharge counting tube having a plurality of cathodes and first and second sets of guide electrodes comprising a first circuit containing resistive components of a first value in series with said first set of guide electrodes, a second circuit containing resistive components of a second value in series with said second set of guide electrodes, a third circuit containing resistive components of a third value in series with at least one of said cathodes, said first value being greater than said second value and said second value being greater than said third value, means for applying an input signal simlutaneously across a first portion of the resistive components in series with said first set of guide electrodes and across a second portion of the resistive components in series with said second set of guide electrodes, said first portion being of greater resistive value than said second portion, a condenser connected in parallel with the resistance components of said first circuit which are not included in said first portion, and means for developing an output signal across the resistive components of said third circuit.

4. A drive circuit for a glow discharge counting tube having an anode, a plurality of cathodes and at least a first and a second set of guide electrodes comprising means for applying a negative input signal to said first set of guide electrodes, means for applying a portion of said negative input signal to said second set of guide electrodes, means for increasing the potential in a positive direction on said first set of guide electrodes in response to transfer of said glow discharge to one of said first set of guide electrodes, and means maintaining the potential on said first set of guide electrodes at an increased positive value for a predetermined period after the transfer of said glow discharge thereto.

5. A drive circuit for a glow discharge counting tube having a plurality of cathodes, an anode, a like plurality of first and a like plurality of second guide electrodes, said guide electrodes being symmetrically arranged between adjacent ones of said cathodes comprising means for applying a negative input signal to said plurality of first guide electrodes, means for applying a portion of said negative input signal to said plurality of second guide electrodes, means for increasing the potential in a positive direction on said plurality of first guide electrodes in response to transfer of glow discharge to one of said first guides, and means for retaining said plurality of first guide electrodes at a potential which is increased in a positive direction for a predetermined period after said glow discharge transfeis to one of said plurality of second guide electrodes.

6. A drive circuit for a glow discharge counting tube having a plurality of cathodes, a plurality of first guide electrodes and a plurality of second guide electrodes comprising means for applying a negative input signal to said plurality of first guide electrodes, means for applying a predetermined portion of said negative input signal to said plurality of second guide electrodes and means for maintaining said plurality of first guide electrodes at a gradually decreasing negative potential for a predetermined period whereby said glow discharge is transferred from one of said plurality of cathodes to one of said plurality of first guide electrodes and thence to one of said plurality of second guide electrodes.

7. Pulse counting apparatus comprising a glow-discharge counting tube having a plurality of circularly arranged cathodes, a plurality of first guide electrodes, and a plurality of second guide electrodes, one of said first guide electrodes and one of said second guide electrodes being disposed between each pair of said cathodes, means for establishing said glow discharge at one of said plurality of cathodes, means for applying a negative input pulse to said plurality of first guide electrodes to cause transfer of said glow discharge from said one of said plurality of cathodes to the one of said plurality of first guide electrodes adjacent thereto, a resistor in series with said plurality of first guide electrodes causing said one of said plurality of first guide electrodes to become less negative as current of said glow discharge flOWs therethrough, means for applying a predetermined portion of said negative input voltage to said plurality of second guide electrodes to cause transfer of said glow discharge from said one of said plurality of first guide electrodes to the one of said plurality of second guide electrodes adjacent thereto as the voltage on said plurality of first guide electrodes becomes less negative than that on said plurality of second guide electrodes by a predetermined amount.

8. Apparatus as in claim 7 including a condenser connected in parallel with said resistor to maintain said plurality of first guide electrodes less negative than said plurality of second guide electrodes and said cathodes for a predetermined period after the transfer of said glow 5 discharge from said one of said plurality of first guide electrodes to said adjacent one of said plurality of second guide electrodes.

9. Pulse counting apparatus comprising a glow transfer tube having a plurality of circularly arranged cath- 10 odes, an anode, a first set of guide electrodes, each guide electrode of said first set being adjacent in a clockwise direction one of said cathodes, and a second set of guide electrodes, each guide electrode of said second set being adjacent in a counter-clockwise direction one of said cathodes, a pair of input terminals, one of said input terminals being grounded, a coupling condenser having one terminal thereof connected to the other of said input terminals, a voltage divider connected between the other terminal of said coupling condenser and said grounded input terminal, a parallel combination of a resistor and condenser also connected to said other terminal of said coupling condenser, means connecting the other terminal of said parallel combination to said first set of guide electrodes, means connecting a point on said voltage divider to said second set of guide electrodes, said cathodes less one being connected directly to said grounded input terminal, said one cathode being connected to an output terminal, a resistor connected between said output terminal and ground, a source of positive direct voltage connected to said anode, a glow discharge taking place between said anode and one of said cathodes, application of a negative input pulse causing said glow discharge to switch from said one of said cathodes to the next adjacent'clockwise one of said first set of guide electrodes,

current flowing through the resistor of said parallel resistor-condenser combination causing charging of said con denser, and increase in a positive direction of Voltage on said one of said first set of guide electrodes, a portion of said applied negative input voltage appearing on said second set of guide electrodes by reason of said connection thereof to said voltage divider, whereby said glow discharge transfers to said next adjacent one of said second set of guide electrodes as the voltage on said one of said second set of guide electrodes becomes more negative by a predetermined amount than the voltage on said first set of guide electrodes, said glow discharge transferring to said next adjacent clockwise main cathode upon cessation of said input pulse.

References Cited in the file of this patent UNITED STATES PATENTS 2,443,407 Wales June 15, 1948 2,714,179 Thomas et a1 July 26, 1955 2,739,266 Burnett Mar. 20, 1956 

